UNIVERSITY   OF    CALIFORNIA 

COLLEGE   OF   AGRICULTURE 

AGRICULTURAL   EXPERIMENT   STATION 

BERKELEY,    CALIFORNIA 

CIRCULAR  311 

December,  1927 

THE  IMPROVEMENT  OF  QUALITY  IN  FIGS' 

EALPH  E.  SMITH2  and  H.  N.  HANSEN3 


The  California  fig  industry  lias  a  serious  problem  in  the  high 
percentage  of  spoilage  in  the  fruit.  This  condition  has  recently  been 
accentuated  by  the  action  of  federal  authorities  in  decreasing  the  legal 
tolerance  of  infested  figs.  The  present  situation  is  not  a  new  one  but 
has  existed  for  a  long  time.  It  has  been  previously  described  as 
follows  :4 

"The  fig  deserves  to  be  one  of  California's  best  commercial  fruits. 
It  shares  with  the  olive  and  grape  the  distinction  of  being  one  of  the 
oldest  cultivated  fruits.  It  is  nutritious,  appetizing,  of  attractive 
appearance,  and  wholesome.  The  fruit  has  a  great  variety  of  uses,  not 
only  in  the  usual  dried  form,  but  also  for  eating  fresh  and  in  such 
manufactured  forms  as  jam,  marmalades,  preserves,  canning,  candy, 
bakery  products,  breakfast  and  health  foods,  beverages  and  medicinal 
preparations.  The  well  known  salutary  properties  of  dried  figs  lend 
themselves  particularly  well  to  advertising.  The  fig  is  one  of  the 
healthiest  of  fruit  trees,  easily  suited  as  to  soil  and  moisture,  and  well 
adapted  to  a  wide  area  in  California  and  (for  dried  figs)  to  no  other 
portion  of  the  United  States.  The  quality  of  California-grown  figs  at 
their  best  is  admittedly  unsurpassed. 

' '  And  yet,  it  must  be  said  that  fig  culture  is  not  as  well  established 
in  California  as  that  of  many  other  fruits,  and  considerable  difficulty 
is  experienced  in  disposing  of  the  comparatively  small  dried-fig  crop 
of  the  state  at  even  moderate  prices 


1  A  paper  delivered  at  the  eleventh  annual  Fig  Institute,  Fresno,  California, 
November  4,  1927.  Published  at  the  request  of  the  permanent  committee  on 
disease  control. 

2  Professor  of  Plant  Pathology  and  Plant  Pathologist  in  the  Experiment 
Station. 

3  Eesearch  Assistant  in  Plant  Pathology. 

4  Phillips,  E.  H.,  E.  H.  Smith,  and  E.  E.  Smith.  Fig  smut.  California  Agr. 
Exp.  Sta.  Bui.  387:1-38.     1925. 


2  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

"The  greatest  obstacle  to  the  success  of  the  fig  industry  at  the 
present  time  is  the  occurrence  of  various  forms  of  rotting,  souring,  and 
molding  of  the  fruit,  which  at  times  become  very  abundant  and 
troublesome,  and  for  which  no  method  of  control  has  been  found. 
Such  defects  reduce  yields  and  make  it  very  difficult  to  put  up  a  high- 
grade,  dependable  pack  of  sufficient  quality  to  compete  on  better  than 
even  terms  with  the  foreign  product  and  one  upon  which  the  arts  of 
advertising  and  salesmanship  can  confidently  be  practiced.  It  is  only 
by  such  advertising,  backed  by  superior,  uniform  quality  that  our 
increased  production  of  other  foreign-competing  fruit  products  has 
been  successfully  marketed." 

The  Experiment  Station  has  for  several  years  been  engaged  in  a 
study  of  fig  troubles,  with  considerable  financial  assistance  from  the 
California  Peach  and  Fig  Growers  Association.  Miss  Phillips  began 
the  work  in  1920.  She  and  Miss  Smith  were  the  first  to  indicate  clearly 
that  the  rotting  and  spoiling  of  figs  in  the  orchard  is  not  an  ordinary 
process  of  decay  or  the  effect  of  weather  conditions,  but  that  there  are 
certain  specific  troubles  or  diseases,  each  with  a  definite  cause  and 
process  of  development.  Their  work  suggested  certain  fundamental 
facts  which  later  investigations  have  proven  to  be  correct.  The  follow- 
ing principles  may  be  considered  as  established:  (1)  The  rotting  of 
figs  is  caused  by  different  kinds  of  fungi,  bacteria,  yeasts  and  similar 
organisms,  which  start  to  develop  inside  the  fruit.  (2)  The  decay 
germs  are  carried  into  the  figs  by  insects;  a  fig  is  always  sound  and 
sterile  unless  it  has  been  entered  by  some  insect.  (This  might  not 
apply  to  figs  which  had  been  rained  on  or  had  lain  on  wet  soil.)  (3) 
Almost  all  the  trouble  starts  while  the  figs  are  still  on  the  tree  and  not 
after  they  have  fallen  to  the  ground.  (4)  The  rotting  or  souring  of 
figs  is  not  caused  by  weather  conditions,  soil  moisture,  or  irrigation, 
but  these  conditions  may  hasten  or  retard  the  trouble  by  causing  the 
figs  to  ripen  and  dry  more  or  less  slowly.  P.  D.  Caldis5  followed  with 
further  investigation  of  fig  troubles.  Agents  of  the  Bureau  of  Ento- 
mology of  the  United  States  Department  of  Agriculture  have  recently 
been  assigned  to  work  on  fig  troubles,  through  the  efforts  of  the  Dried 
Fruit  Association  of  California. 

At  a  meeting  of  fig  growers  held  recently  in  Fresno,  resolutions 
were  adopted  urging  the  continuation  of  all  this  work  and  requesting 
the  Director  of  the  State  Department  of  Agriculture  to  take  the  lead 
in  an  effort  toward  improving  the  fig  situation.  This  paper  has  been 
prepared  for  the  purpose  of  bringing  together  in  a  brief  form  what  is 


s  Caldis,  P.  D.     Etiology  and  transmission  of  endosepsis   (internal  rot)   of 
the  fruit  of  the  fig.     Hilgardia  2:287-328,  16  pi.     1927. 


CIRC.  311]  THE   IMPROVEMENT    OF    QUALITY   IN    FIGS 


Fig.  1. — Interior  of  ripe  Calimyrna  figs  with  endosepsis. 
(From  Hilgardia,  Vol.  2,  No.  7.) 


4  UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION 

known   about   these   fig   troubles,   their   nature   and   cause,    and   the 
possibilities  of  controlling  them. 

The  principal  troubles  affecting  figs  in  the  orchard  are  certain 
specific  forms  of  rotting  or  spoiling  of  the  fruit,  most  important  of 
which  are  those  called  endosepsis  (brown  rot,  internal  rot)  souring, 
smut  and  mold. 


Fig.  2. — Dried  Calimyrna  figs  showing  the  dark  ends  which  indicate  endosepsis. 
(From  Hilgardia,  Vol.  2,  No.  7.) 


CIRC.  311]  THE    IMPROVEMENT    OF    QUALITY    IN    FIGS 


Fig.  3. — Interior  of  dried  figs  affected  with  endosepsis,  showing  the  hollow, 
seedy  condition.     (From  Hilgardia,  Vol.  2,  No.  7.) 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


ENDOSEPSIS     (BROWN    ROT,    INTERNAL    ROT) 

This  is  a  rot  affecting  the  Calimyrna  or  any  other  fig  which  has 
been  caprified  by  the  Blast ophaga  wasp.6  As  the  fig  ripens  there 
develops  in  the  flesh  a  brown,  watery  form  of  decay  (fig.  1).  There 
is  no  very  bad  odor  or  disagreeable  flavor  unless  this  disease  is  com- 
plicated with  other  forms  of  rot.     Only  caprified  figs  are  typically 


Fig.  4. — The  female  blastophaga  enlarged  twenty-seven  times. 
(From  Bulletin  319.) 

affected.  The  inside  of  the  dried  fig  becomes  dark-colored  and  hollow, 
containing  little  pulp  but  mostly  seeds  (figs.  2  and  3) .  Many  caprified 
figs  become  affected  with  both  endosepsis  and  souring  or  other  rots, 
Cause. — The  rot  is  caused  by  a  white  fungus  which  does  not  form 
a  conspicuous  mold  in  affected  figs.     The  spores  of  this  fungus  are 


6  Condit,  I.  J.     Caprifigs  and  caprification. 
319:341-377.     1922. 


California  Agr.  Exp.  Sta.  Bui. 


CIRC.  311]  THE    IMPROVEMENT    OF    QUALITY    IN    FIGS  7 

carried  by  the  blastophaga  from  one  generation  of  caprifigs  to  another 
and  thence  to  the  edible  crop  (fig.  4).  The  fungus  grows  mostly  on 
the  blossom  parts  just  inside  the  eye  of  the  caprifig.  When  the  female 
blastophaga  passes  out,  some  of  the  spores  stick  to  her  wings  (fig.  5). 
In  entering  another  fig  she  brushes  off  some  of  these  spores  on  the 

I  I       I 

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Fig.  5. — Portion  of  a  wing  of  the  female  blastophaga,  much  enlarged,  showing 
the  tiny,  white  fungus  spores  among  the  black  spines. 

flowers  or  bud  scales  (fig.  6).  Often  there  is  quite  an  accumulation  of 
dead  blastophagas  and  wings  just  inside  the  eye,  and  this  makes  a 
good  starting  point  for  the  fungus  (fig.  7). 

Caldis  found  that  all  parts  of  the  state  are  infested  with  this 
fungus  and  that  it  is  probably  in  every  caprifig  tree  in  the  state  and 
in  most  of  the  individual  caprifigs.  He  proved  beyond  all  question 
that  it  is  the  blastophaga  which  carries  the  fungus  into  the  Calimyrna 
figs  and  that  it  comes  from  the  caprifigs  (fig.  8). 


8  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Control. — The  only  conceivable  way  of  preventing  endosepsis  in 
caprified  figs  is  to  obtain  blastophagas  or  caprifigs  free  from  the 
fungus,  if  such  a  thing  is  possible.  For  this  seemingly  hopeless  task 
several  promising  methods  have  been  discovered.  It  is  evident  that 
in  any  method  of  using  clean  blastophagas  a  district  must  be  chosen 


Fig.  6. — The  largest  figs  in  the  illustration  are  mamme  figs  from  which  the 
blastophagas  are  issuing.  The  four  smaller  figs  at  the  tip  of  the  branch  are 
profichi  figs  of  sufficient  size  for  the  female  insects  to  enter  and  oviposit.  Note 
the  female  blastophagas  on  the  surface  of  the  fruit.  They  carry  the  spores  of 
the  endosepsis  fungus  on  their  wings  from  the  mamme  to  the  profichi  and  from 
the  profichi  to  the  edible  figs  and  mammoni.     (From  Bulletin  319.) 


which  is  out  of  flying  range  of  blastophagas  from  any  untreated  area 
or  caprifig  trees,  and  all  the  caprifigs  in  the  district  must  be  treated 
or  destroyed  in  order  to  get  100  per  cent  results.  An  individual 
grower  or  district  may  do  some  good  by  working  alone,  but  the  results 
will  vary  according  to  the  number  of  infested  blastophagas  that 
drift  in. 


CIRC.  311]  the    IMPROVEMENT    OF    QUALITY    IN    FIGS  9 

Demonstrations  of  1927. — In  one  demonstration  during  the  past 
season  an  area  of  about  a  square  mile  just  east  Of  Modesto  was  chosen. 
In  this  area  there  were  six  fig  growers  and  a  total  of  seventy-five  capri 
fig  trees  and  fifty  acres  of  Calimyrnas.     The  area  was  fairly  well  iso- 


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Fig.  7. — Section  of  a  caprifig,  somewhat  enlarged.  The  female  blastophaga, 
in  entering  such  a  fig,  brushes  off  spores  of  the  endosepsis  fungus  from  her 
wings  onto  the  scales  and  florets.  The  fungus  develops  here,  and  when  the 
new  generation  of  blastophagas  emerge  they  pick  up  the  spores  again  and 
carry  them  on  to  the  next  crop  of  figs.  By  treating  the  inside  of  the  fig  with 
a  disinfectant,  either  by  injecting  it  or  splitting  and  dipping,  the  fungus  is 
killed,  but  the  insects  in  the  galls  are  not  injured.  No  pollen  is  required  from 
the  mamme  to  set  the  profichi. 

lated  from  other  caprifigs,  especially  to  windward,  although  there  were 
trees  in  various  directions  within  one  mile.  A  careful  survey  was  made 
to  locate  all  the  caprifig  trees  in  the  area  and  as  soon  as  the  leaves  were 
off  in  the  fall  most  of  the  figs  (mamme)  were  removed  from  the  trees, 


10 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  8. — Culture  plates  showing,  A,  a  section  of  a  plate  with  insects  from  dis- 
infected mamme  fig,  with  no  fungus  growth  (the  blastophaga  on  the  left  shows 
a  slight  development  of  bacteria)  ;  B  and  C,  the  growth  of  endosepsis  fungus  from 
blastophagas  from  untreated  figs. 


Circ.  311] 


THE    IMPROVEMENT    OF    QUALITY    IN    FIGS 


11 


leaving  a  few  on  some  of  the  smaller  trees  for  treatment  (fig.  9). 
During  January  and  February  these  reserved  figs  were  treated  on  the 
tree  by  injecting  each  one  through  the  eye  with  a  fungicidal  solution 
by  means  of  a  hypodermic  syringe.  Culture  tests  showed  that  it  was 
possible  by  this  method  to  kill  the  fungus  in  the  mamme  figs  com- 
pletely without  injuring  the  figs  or  the  insects  in  the  galls.  Some  of 
the  growers  had  contracted  for  caprifigs  on  trees  in  other  places. 
These  trees  were  treated  in  the  same  way,  removing  most  of  the 
mamme  figs  and  injecting  the  remainder.   In  the  large  caprifig  orchard 


Fig.  9. — A  Milco  caprifig  tree  showing  the  mamme  crop  which  must  be  removed 
and  destroyed  or  treated  in  order  to  eradicate  endosepsis.     (From  Bulletin  319.) 

of  the  Fig  Association  at  Orosi  most  of  the  mamme  figs  were  removed 
and  the  remainder  treated.  In  other  cases  isolated  capri  trees  were 
entirely  stripped  and  recap rified  with  the  injected  figs  from  other 
places.  In  these  cases  the  treated  figs  were  left  on  the  trees  until 
maturity,  then  removed  and  hung  in  the  trees  to  be  caprified,  in  order 
to  get  a  clean  profichi  crop. 

The  hypodermic  injection  method  of  treatment  had  the  advantage 
of  being  practically  100  per  cent  effective  in  disinfecting  the  figs  but 
had  certain  very  serious  disadvantages  for  work  on  a  large  scale.  The 
method  is  very  slow  and  would  require  a  corps  of  several  hundred 


12  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

trained  men  to  cover  a  large  district.  The  operation  requires  con- 
siderable skill.  It  is  easy  to  miss  some  of  the  mamme  figs  on  the  trees 
and  leave  them  untreated.  Most  mamme  figs,  at  the  time  when  the 
injection  should  be  done,  are  very  solid  and  hard  and  difficult  to 
inject.     The  method  is  not  practical  for  any  large  area. 

The  control  of  endosepsis  was  also  tried  in  1927  in  two  compara- 
tively isolated  Calimyrna  orchards,  one  near  Merced  and  one  near 
Madera.  In  the  latter  a  somewhat  different  method  was  used.  All 
the  mamme  figs  in  the  orchard  were  stripped  off  and  in  another, 
isolated  place  mammes  were  left  on  the  trees  until  they  commenced  to 
soften  and  mature  and  the  insects  were  beginning  to  emerge;  then 
these  figs  were  removed,  cut  in  two,  and  soaked  in  the  disinfecting 
solution  for  about  fifteen  minutes.  These  pieces  were  then  put  into 
baskets  and  hung  in  the  trees  as  usual. 

This  method  has  the  advantage  of  being  rapid  and  requiring  no 
particular  skill.  A  serious  disadvantage  is  that  the  mamme  figs  which 
are  to  be  treated  must  be  left  on  the  trees  until  they  are  mature  before 
they  can  be  taken  off,  split,  and  dipped.  Consequently  before  the  figs 
are  picked  some  infested  blastophagas  will  escape  and  contaminate  the 
profichi  in  that  vicinity.  That  area  will  then  have  to  be  cleaned  up 
the  following  year.  It  would  be  ideal  if  all  the  mamme  figs  in  the  fig- 
growing  districts  could  be  stripped  off  and  enough  mamme  for  dis- 
infecting and  recolonizing  be  obtained  in  distant  places  where  no 
edible  figs  are  grown.  Unfortunately,  there  are  not  enough  caprifigs 
in  such  places  to  recaprify  the  whole  San  Joaquin  Valley. 

Another  difficulty  is  that  figs  thus  treated  are  not  permanently 
disinfected ;  some  of  the  fungus  may  be  alive  down  deep  in  the  tissues 
and  grow  out  again  to  the  surface.  Consequently,  the  dipped  figs 
which  are  hung  in  the  trees  for  caprification  must  be  taken  out  again 
and  destroyed  at  the  end  of  five  days.  Some  of  these  might  easily  be 
overlooked  and  the  later  blastophagas  which  come  from  them  might 
then  get  infested  with  the  fungus  and  infect  the  profichi.  If  the  figs 
are  picked  and  dipped  early,  say  30  days  before  maturity,  the  insects 
will  not  emerge  normally  at  the  proper  time. 

In  the  Modesto  orchards  it  was  necessary  to  bring  in  extra  profichi 
figs.  These  came  from  the  Orosi  orchard  which  was  exposed  to  infec- 
tion from  outside  caprifigs.  Consequently  these  figs  were  not  entirely 
clean.  All  the  demonstration  orchards  showed  less  than  5  per  cent 
endosepsis  in  the  total  crop,  the  figs  being  very  much  better  than  those 
of  any  other  orchard  examined  in  1927,  or  those  in  the  same  orchards 
in  past  years. 


ClRC.  311]  THE    IMPROVEMENT    OF    QUALITY    IN    FIGS  13 

A  New  Plan:  Obtaining  Clean  Blast  ophaga  by  the  Insect ary 
Method. — A  new  plan  has  recently  been  devised  by  the  junior  author 
by  which  all  the  mamme  figs  in  the  state  (or  in  the  area  to  be  handled) 
would  be  removed  from  the  trees  at  least  30  days  before  maturity  and 
shipped  to  an  insectary  in  a  central  place  where  no  blastophagas  could 
escape  to  any  caprifig  trees.  There  the  figs  would  be  stored  and  dis- 
infected by  the  dipping  method.  By  the  use  of  proper  equipment 
and  by  application  of  heat,  the  insects  at  the  proper  time  would  be 
made  to  emerge  into  sterile  vials  or  containers  in  which  they  might  be 
shipped  to  any  part  of  the  state  and  placed  in  the  trees  to  caprif y  the 
profichi  crop  (fig  10).  This  method  would  make  it  unnecessary  to 
remove  any  treated  figs  from  the  trees,  furnish  almost  limitless  num- 
bers of  clean  blastophagas  and  allow  of  cleaning  up  the  whole  territory 
in  one  season.  It  is  the  most  scientific  method  which  has  yet  been 
suggested,  and  the  only  one  which  would  be  practical  for  a  large  area. 
It  would,  of  course,  need  extensive  trying  out  before  it  could  be  con- 
sidered as  completely  perfected,  but  many  parasitic  insects  are  handled 
in  this  way  with  perfect  success,  and  the  methods  of  such  work  are 
already  highly  developed.  Preliminary  tests  have  shown  that  blasto- 
phagas will  live  in  glass  vials  for  more  than  two  weeks  and  that  they 
can  be  kept  dormant  by  chilling  with  ice. 

Possibilities  of  State-wide  Control. — It  is  now  proposed  to  carry 
out  a  state-wide  or  valley-wide  cleanup  of  endosepsis.  This  is  a  far 
greater  task  than  the  control  of  the  disease  in  a  single  district.  It  is  a 
task  which  should  only  be  undertaken  on  the  assumption  that  a  crisis 
exists  and  that  radical  action  is  therefore  necessary.  Neither  the  State 
Department  of  Agriculture  or  the  University  has  any  reason  to  sug- 
gest or  promote  such  a  procedure  save  at  the  urgent  desire  of  the 
industry.  In  the  former  experiments  all  the  growers  agreed  to  submit 
their  trees  to  the  treatment  and  all  the  work  was  personally  super- 
vised. As  the  area  treated  was  so  small  it  was  possible  to  get  plenty 
of  mamme  figs  in  other  places  for  treatment.  Even  in  this  small  area 
and  under  careful  supervision  it  was  very  difficult  to  locate  all  the 
caprifig  trees  and  to  find  and  remove  every  single  fig.  In  fact,  some 
figs  and  even  a  few  trees  were  missed. 

In  order  to  carry  out  any  general  control  of  endosepsis  the  work 
must  be  done  very  systematically,  extremely  thoroughly,  and  under 
legal  authority.  The  only  agencies  having  the  power  and  organization 
to  do  this  are  the  State  Department  of  Agriculture  and  the  County 
Horticultural  Commissioners.  Many  details,  such  as  whether  or  not  a 
charge  should  be  made  for  clean  blastophagas,  how  to  allocate  these 


14 


UNIVERSITY    OF    CALIFORNIA— EXPERIMENT    STATION 


•>  * 


K 


Fig.  10.— Clean  blastophagas  in  glass  vial  as  used  in  new  method 
to  capnfy  profichi  crop. 


CIRC.  311]  THE   IMPROVEMENT   OF   QUALITY   IN   FIGS  15 

fairly,  how  to  handle  the  expense  of  treating  and  distribution,  and 
similar  questions  would  have  to  be  settled  by  mutual  consent  of  the 
interested  parties.  It  should  be  understood  that  no  extensive  campaign 
of  this  sort  has  ever  yet  been  attempted  and  that  unf  orseen  difficulties 
might  easily  arise  to  prevent  complete  success,  if  eradication  of  endo- 
sepsis  over  large  areas  at  one  time  is  undertaken.  The  methods  will 
undoubtedly  be  improved  by  further  experience  in  many  of  the  details 
of  the  work.  If  a  state- wide  campaign  is  attempted  there  would  be 
some  possibility  of  a  shortage  in  the  next  profichi  crop.  Growers 
would  have  to  take  this  chance  as  being  better  than  having  a  full 
supply  of  ordinary  infected  caprifigs.  The  whole  question  is  whether 
the  situation  is  bad  enough  to  take  a  chance  on  imperfect  results  for 
one  year  in  order  to  start  on  an  extensive  scale. 

With  the  insectary  method  of  disinfection,  the  following  pro- 
cedure would  be  necessary:  (1)  Make  a  complete  survey  and  locate 
every  caprifig  tree  and  graft  in  the  area.  This  would  require  a  house- 
to-house  and  orchard-to-orchard  inspection.  (2)  Before  February 
15th  go  over  all  the  capri  trees  and  remove  every  mamme  fig  or  destroy 
the  trees.  Very  careful  inspection  is  required  to  find  every  fig,  espe- 
cially on  large  trees.  There  are  many  large,  old  trees  where  it  would 
be  absolutely  impossible  to  remove  all  the  figs,  and  either  the  whole 
tree  or  the  top  would  have  to  be  cut  off  and  burned.  (3)  Send  the 
mamme  figs  to  the  central  insectary  for  treatment,  or,  if  not  needed, 
they  should  be  destroyed.  No  caprifigs  should  be  dropped  on  the 
ground  under  the  trees  and  allowed  to  remain  there  as  the  infested 
blastophagas  might  live  over  in  them  and  enter  the  profichi.  (4)  In 
the  insectary,  the  mamme  figs  would  be  stored  in  a  cool  place  with 
proper  humidity  until  caprification  time.  Then,  as  the  blastophagas 
are  needed,  the  figs  would  be  split  in  two,  dipped  in  the  fungicide, 
and  placed  in  warm  chambers  at  the  proper  temperature  to  cause  the 
insects  to  emerge.  The  female  blastophagas  would  be  caught  in  sterile 
vials  and  shipped  out  to  the  growers.  If  necessary  they  could  be  kept 
dormant  by  cold  and  held  in  storage.  Enormous  numbers  of  clean 
blastophagas  could  be  obtained  by  this  method  and  the  grower  could 
be  furnished  with  an  abundant  supply  for  the  profichi  crop.  The 
latter  would  be  distributed  and  handled  as  usual  to  caprify  the 
Calimyrna  figs. 


16 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


SOURING 

It  should  be  clearly  understood  that  endosepsis  is  not  the  only  fig 
disease;  other  troubles  are  also  very  serious.  Even  with  a  complete 
elimination  of  endosepsis  there  would  still  be  many  bad  figs.  A  really 
successful  solution  of  the  present  fig  problem  would  require  the  control 
of  at  least  one  other  disease — that  called  souring. 


Fig.  11. — Sour  fig. 

This  is  a  form  of  spoilage  in  figs  in  which  the  contents  of  the  ripe 
fruit  ferment  and  sour,  and  liquid  drips  from  the  eye  (fig.  11).  The 
dried  fig  is  hollow  and  has  a  sour  taste  and  odor.  The  outside  is 
shrivelled  and  discolored  in  a  more  or  less  typical  way.  The  conditions 
called  'blue  stem/  'black  neck/  and  'black  end'  in  dried  Adriatic  figs 
are  caused  by  souring  (fig.  12).     Figs  with  endosepsis  may  also  be 


CIRC.  311] 


THE    IMPROVEMENT    OF    QUALITY    IN    FIGS 


17 


affected  with  souring.  Of  the  commercial  fig  varieties  in  California 
the  Adriatic  and  Calimyrna  are  most  liable  to  souring,  while  the  Black 
Mission  and  Kadota  are  very  free  from  the  trouble. 

Cause. — Souring  is  caused  by  yeast,  followed  by  the  action  of 
bacteria  and  molds.  It  is  started  by  insects,  especially  the  dried-fruit 
beetle  (Carpophilus  hemipterus),  entering  the  figs.  It  is  spread  by 
these  and  other  insects,  especially  the  vinegar  fly,  Drosophila.     The 


h&* 


' 


Fig.  12. — Sour  figs  dried  on  tree,  showing  'black-neck,'  ' blue-stem'  and 
'black-end'  conditions. 

beetles  breed  throughout  the  year  in  decaying  fruit  of  all  kinds  where 
they  become  contaminated  with  yeasts  and  other  decay-producing 
organisms.  They  then  enter  the  figs  and  start  the  trouble  there.  That 
the  Mission  and  Kadota  figs  are  less  affected  by  souring  than  other 
varieties  is  due  to  the  fact  that  the  eye  of  the  fruit  is  too  small  to  allow 
the  beetle  to  enter. 

Control. — Control  of  the  dried-fruit  beetle  is  probably  the  secret 
of  the  prevention  of  souring.  Sanitary  methods,  such  as  the  cleaning 
up  of  all  refuse  fruit  material  in  the  vicinity  of  fig  orchards  should 
be  strongly  emphasized.     Often  a  few  cull  oranges  (fig.  13),  decaying 


18 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  13. — Dried-fruit  beetles  issuing  from  decaying  orange,  covered  with  disease 
germs  and  ready  to  attack  figs.     (From  Bulletin  387.) 


CIRC.  311]  the   IMPROVEMENT   OF   QUALITY   IN   FIGS  19 

melons  (fig.  14)  or  thrown  out  lemon  halves  contain  hundreds  of  these 
insects  ready  to  invade  the  figs  and  loaded  with  fungus  spores,  yeasts, 
and  bacteria.  Miss  Phillips7  found  that  the  following  list  represents 
a  typical  menu  for  these  insects  during  the  year  at  Fresno. 

November-March — 

Figs,  all  kinds  and  conditions. 

Melons,  fermenting  and  molding. 

Apples,  rotting  on  ground. 
April — 

Prunes,  old,  in  packing  house. 

Apples,  in  dump  and  under  trees. 

Oranges,  on  ground  under  trees. 

Melons,  decaying  in  field. 
May — 

Oranges,  on  ground  under  trees. 

Figs,  old  culls  in  dry  yard. 
June — 

Figs,  old  culls  in  orchard. 

Oranges,  on  ground  under  trees. 

Grapefruit,  culls  on  ground. 
July — 

Figs,  Cordelia  variety,  fresh,  ripe,  sound,  and  sour. 
Mission,  moldy,  first  crop  on  ground  under  tree. 
Old  culls,  on  ground  near  fig  orchard. 
Brunswick  variety,  first  crop,  both  sound  and  sour. 
Kadota  variety,  first  crop,  sour. 

Peaches,  ripe,  on  ground. 

Apricots,  ripe,  rotted  by  smut  fungus. 

Tomatoes,  ripe  and  moldy. 
August — 

Apples,  rotting  on  ground,  infested  with  worms,  and  various  molds, 
including  smut  fungus. 

Melons,  fermenting  and  moldy,  smut  fungus  present. 

Figs,  Adriatic  variety,  sound,  souring,  moldy,  and  smutty. 
Kadota  variety,  both  sound  and  sour. 

Peaches,  fermenting  and  rotting,  smut  fungus  present. 

Plums,  like  peaches. 

Pears,  wormy,  rotting,  and  fermenting. 
September — 

Figs,  Calimyrna,  Kadota,  and  Adriatic  varieties,  sound,  souring,  rot- 
ting, moldy,  and  smutty,  both  on  trees  and  ground. 
October — 

Figs  and  other  fruits,  all  kinds  and  conditions,  many  souring,  moldy, 
and  smutty. 

Every  effort  should  be  made  to  clean  up  all  such  material  as  the 
above  in  the  vicinity  of  fig  orchards  before  the  crop  begins  to  ripen. 


7  Phillips,  E.  H.,  E.  H.  Smith,  and  E.  E.  Smith.     Loc.  cit. 


20 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  14. — Old  melons  in  field  near  fig  orchard,  furnishing  abundant  supply  of 
dried  fruit-beetles  and  germs  of  decay.     (From  Bulletin  387.) 


ClRC.  311]  THE    IMPROVEMENT    OF    QUALITY    IN    FIGS 


21 


r 


B 


Fig.  15. — Smut  in  Adriatic  figs.    A,  interior;  B,  exterior.    (From  Bulletin  387.) 


22 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


SMUT 

In  this  disease  the  inside  of  the  ripe  fig  is  partially  filled  with  a 
black,  dusty,  mold  fungus  (fig.  15). 

Cause. — Smut  is  caused  by  the  common  black  mold  fungus,  Asper- 
gillus niger.  Its  spores  are  usually  carried  into  the  figs  by  dried-fruit 
beetles  which  come  from  old  rotting  fruit  on  which  this  and  other 
molds  are  growing  (fig.  16). 


Fig.  16. — Culture  plate  in  which  a  dried-fruit  beetle  was  placed,  resulting 
in  abundant  growth  of  molds,  yeast,  and  bacteria.  The  black-dot  areas  are 
the  smut  fungus. 


Control. — Control  of  smut  is  to  be  accomplished  by  the  same 
method  as  that  of  souring,  namely,  eradication  of  the  dried-fruit 
beetle  and  insects  of  similar  habits,  by  cleaning  up  all  their  food 
material,  and  by  trapping. 


CIRC.  311]  THE   IMPROVEMENT    OF    QUALITY    IN    FIGS  23 


MOLD 

Many  dried  figs  are  found  to  contain  molds  of  various  sorts,  green, 
white,  brown,  black,  and  other  colors.  These  also,  to  the  best  of  our 
knowledge,  are  mainly  started  by  the  dried-fruit  beetle  and  the  pre- 
vention of  this  sort  of  trouble  will  be  largely  brought  about  by  the 
suppression  of  such  insects. 


SUMMARIZED  DIRECTIONS  FOR  IMPROVING  THE  QUALITY  OF  FIGS 

1.  Destroy  all  unnecessary  caprifig  trees.  Keep  caprifigs  away 
from  Missions,  Kadotas,  and  Adriatics. 

2.  Cooperate  with  the  County  Horticultural  Commissioner  and 
Inspectors  in  whatever  plan  is  adopted  for  cleaning  up  the  mamme 
crop.    Do  whatever  they  ask  cheerfully,  promptly,  and  thoroughly. 

3.  Destroy  every  particle  of  rotten  fruit,  old  dried  fruit,  and 
similar  material  near  the  fig  orchard.  This  includes  old  caprifigs  in 
baskets.  Look  for  anything  which  harbors  dried-fruit  beetles  and 
vinegar  flies.  \    \    \ 

4.  Keep  in  touch  with  the  experiments  being  made  at  Fresno  on 
the  control  of  these  insects  at  the  Dried  Fruit  Insect  Laboratory  of  the 
United  States  Department  of  Agriculture. 

5.  Keep  the  ground  beneath  the  trees  clean  and  dry  during  the 
harvest  time. 

6.  Do  not  shake  the  trees,  but  let  the  figs  get  as  dry  as  possible 
before  they  drop. 

7.  Pick  up  the  figs  frequently,  every  day  if  possible. 

8.  Do  not  leave  bad  figs  on  the  ground  but  pick  them  up  separately 
from  the  good  figs  and  destroy  them. 

9.  Do  not  dip,  wash,  or  wet  the  figs  unless  required  to  do  so  by 
the  packer. 

10.  Deliver  the  dried  figs  promptly  to  the  packer.  Do  not  keep 
them  stored  in  barns  or  sheds. 


